PurePontiacKid Posted July 8, 2012 Share Posted July 8, 2012 So I've recently swapped my 280ZX to SUs, and now that it's summer-time in Vegas, temps are going 100*+ and on my drive home I'm noticing my idle quality drops off, the car misses when I'm accelerating, etc. Basically all the symptoms of vapor-lock/fuel percolation. I've got my SU's with the stock fuel rail that I have wrapped in heat-reflecting tape, have wrapped the float-bowls in heat-reflecting tape, and have a good condition stock heatshield that has been powder coated and covered in heat-reflecting tape on the side of the header, and also about the first 8" of the header primaries have been wrapped in header-wrap. I've also got the stock clutch fan, along with a pusher e-fan, and a Koyo radiator. Coolant levels never get above half on my temp gauge. The car drives around great in the morning, only driving around during the hottest parts of the day does this happen. I've done nearly everything I can think of to keep heat down in the engine bay, and yet the entire bay still seems hotter than when I had the EFI and no header wrap at all. Is this something I'm just going to have to live with? I suppose I could try and make a second heat-shield that goes underneath the carbs better, and wrap some more of the header, or am I just running in circles at this point? Thanks! Quote Link to comment Share on other sites More sharing options...
JMortensen Posted July 8, 2012 Share Posted July 8, 2012 If you're using a mech fuel pump, get rid of it. Get rid of the rail and run a rubber hose instead. I ran mine from the filter in the front corner of the engine bay across the rad support and then back to the carbs. I don't know where the lines run in the ZX, but I'm sure it's something similar. I had vapor lock issues with the SU's before those two mods, never had trouble after. Quote Link to comment Share on other sites More sharing options...
PurePontiacKid Posted July 8, 2012 Author Share Posted July 8, 2012 I'm using an Aeromotive electric fuel pump in the stock ZX location, near the fuel tank. I was running a rubber hose, but probably in the worst spot, behind the motor... I'll see if there's a way I can neatly route some hoses across the rad support. Thanks for the reply! Quote Link to comment Share on other sites More sharing options...
JMortensen Posted July 8, 2012 Share Posted July 8, 2012 Rubber hose instead of the fuel rail. Just making sure you got that part. Quote Link to comment Share on other sites More sharing options...
PurePontiacKid Posted July 8, 2012 Author Share Posted July 8, 2012 yeah I got that, I've got insulated rubber hose to boot. this is what it used to look like, with the hose routed behind the engine instead of in front: and this is what my current set-up looks like: Quote Link to comment Share on other sites More sharing options...
BluDestiny Posted July 9, 2012 Share Posted July 9, 2012 Why did you switch to the stock rail? were you having this problem with the rubber hoses routed behind the motor? Quote Link to comment Share on other sites More sharing options...
PurePontiacKid Posted July 9, 2012 Author Share Posted July 9, 2012 I switched because the rail will keep less fuel near the carburetors just sitting still, which I think was part of the problem with the way I had the previous hoses routed. All of that fuel was just sitting in the hoses until the motor used it, which made the fuel build up a bunch of heat before it even got to the carbs. And actually, I built a super simple heats hield that bolts to the bottom of the stock heat shield which, so far, seems to have pretty much gotten rid of my problems thus far, even in the 110+* weather on my way home from work today. Quote Link to comment Share on other sites More sharing options...
BLOZ UP Posted July 9, 2012 Share Posted July 9, 2012 (edited) My Aeromotive pump just flows so much that it's causing vapor issues on my EFI system. After about 30 minutes of driving in the Texas heat, I'm hearing the pump get louder and louder, due to (I'm guessing) vapor forming near the inlet. I installed a cheap "Fuel Cooler" out of a $20 tube and fin transmission cooler from O'Reilly's. This allowed me 45 minutes or so of driving. As an intermediate solution, I made and installed a PWM fuel pump speed controller. It worked awesome for about an hour, then the 555 timer decided to crap out (I'm guessing from massive flyback voltage, which I had just finished adding a diode to try and fix). What I need to do is install a sump. Uh, I guess my point is that, depending on what pump you have, you should see if your tank is just heating up a lot. I don't have vapor issues at the rail, that I can tell. It never drops pressure or coughs, just sounds like my pump is destroying itself. Edited July 9, 2012 by BLOZ UP Quote Link to comment Share on other sites More sharing options...
PurePontiacKid Posted July 10, 2012 Author Share Posted July 10, 2012 Indeed, I think this is another issue with my setup now that my carburetors are sorted out. I can definitely tell the difference between vapor lock and fuel percolation. I only really experienced the vapor lock on a lengthy, HARD drive on a rural road, and just getting out of the throttle for a couple of seconds would allow the car to run properly again. I've been told that the pump to get to get rid of vapor lock is a Carter pump, I have yet to look at them yet, however (getting rid of my $200 Aeromotive pump stings a little too much still haha). I don't think that really helps with your EFI stuff, though. Quote Link to comment Share on other sites More sharing options...
PurePontiacKid Posted July 10, 2012 Author Share Posted July 10, 2012 A friend of mine wanted to see what I had done, so I took a couple pics as it sits, here is my heat shield: Quote Link to comment Share on other sites More sharing options...
19762802+2 Posted July 10, 2012 Share Posted July 10, 2012 (edited) Are you running the carb's without filters like that? it's possible you're just sucking in lots of hot engine bay air, You could build a box off the carbs and run some ducting to the front like on some of the 510's and race cars. Also changing your fluid in domes might help some too, I noticed a difference between hot and cold when I was running 10-30 in my carbs. Possibly float level? Edited July 10, 2012 by 19762802+2 Quote Link to comment Share on other sites More sharing options...
PurePontiacKid Posted July 10, 2012 Author Share Posted July 10, 2012 I run with or without a pair of K&N filters, not really a big difference with or without them, I don't really fel like sourcing a stock box lol I have considered extending my new heatshield to the hole where the intake used to run, but meh haha I'm probably using the wrong oil in the carbs for this heat, too. 0W-20 per a friend's reccomendation, might switch to ATF and try that out. float level has been set, per this website: http://datsunzgarage.com/engine/ Quote Link to comment Share on other sites More sharing options...
madkaw Posted July 10, 2012 Share Posted July 10, 2012 Have you wrapped your pump and outlet hose with heat wrap near your tank? Next time you take a long drive, jack the car up and feel around your tank and pump-you will be suprised how hot it is under there. Your diff puts out a ton of heat and bakes verything around it. Check all your rubber hoses because if they are too close to the diff and too old they will get soft under the heat. Also lay your hand on the gas tank, you would be suprised how hot it gets--almost scary! I noticed all this stuff when I was having issues with my daughter's ZX. In the end it turned out to be a partial blockage of my return line at the sending unit. I was just amazed how much heat was under there. Quote Link to comment Share on other sites More sharing options...
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